Electrochemistry in orbit

The International Space Station (ISS), launched in 1998, is a modular satellite in low orbit around the Earth, which is visible even with the naked eye.

Since November 2, 2000, the ISS has had a constantly revolving crew from a variety of nations, working on projects to further push the boundaries of our knowledge. Aside from their important scientific duties, these astronauts must live their daily lives like us – exercising, relaxing, cleaning, and sleeping – albeit in microgravity.

I am a senior graduate student in the Department of Chemistry at University of Puerto Rico (UPR). I am working on a research project in collaboration with NASA, titled «Elucidating the Ammonia Electrochemical Oxidation Mechanism via Electrochemical Techniques at the ISS», or «Ammonia Electrooxidation Lab at the ISS (AELISS)» for short. The purpose of this project is to improve the water processing system and to identify new technology for long-term missions in space.

The project is attributed to NASA-ESPCoR, University of Puerto Rico, University of Alicante, NuVant Systems, and Nanoracks, with support from Metrohm DropSens.

Read more about the project on the NASA website:

Read about AELISS on nasa.gov

Here, you can see the Metrohm DropSens instruments used for this study: the screen-printed carbon electrode (SPCE, 8X110) and its corresponding flow-cell (FLWCL8X1C).

About five years ago, the groups from the University of Alicante and the University of Puerto Rico (UPR) began working together on microgravity experiments which led them to collaborate again for this project, which now resides on the ISS.

The electrochemical oxidation of ammonia using platinum as a catalyst is a well-established reaction, first published almost two decades ago by José’s group. The ammonia is extremely sensitive to the surface structure of platinum. However, this is well-known on earth. How does this reaction process behave in a microgravity environment? The groups sought to determine this by performing experiments in the US using a special airplane which mimics weightlessness for brief periods by flying in a parabolic motion.

At first, this was purely for research, but later Camila’s group in Puerto Rico thought more about its potential use in space. Urea from urine is converted to ammonia, which then goes through the electrochemical oxidation process, resulting in N₂ gas, water, and energy. Perhaps it was possible to use this technology to improve the onboard water recovery and recycling system in the ISS and other spaceships?

Because the UPR group often writes research proposals that are funded by NASA, they are quite knowledgeable in this area regarding the project requirements, as well as what materials are allowed on board a mission. The UPR group has been working in conjunction with NASA for about 20 years.

The final goal of this research is to determine how gravity affects the oxidation of ammonia, and also to test out different catalysts for the reaction in microgravity. While several other parameters can be adjusted in the lab such as pH, nanoparticle shape, and more – gravity is a universal constraint we cannot avoid. On Earth, we are only able to mimic the effects of microgravity for a few seconds with freefall. The previous collaboration between the groups in this project also involved performing experiments on special flights that allowed weightless conditions for less than 15 seconds at a time. This is certainly not enough time to draw long-term conclusions, and hence the push to launch the project into orbit. Only then can a true comparison be made, and conclusions drawn about the effects of gravity and the future applicability of this technology.